Reworked psi[] lf[] and isa[] access syntax for all CSAs

Previously the access to the inverse permutation of for example psi (which is lf) was very counter intuitive as it used the operator(). Now there are separate objects in all csa classes which provide this functionality. For example:

```
j = csa.lf[i];
i = csa.isa[k];
```

this should make the library more useable.